<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>列表 && key</title>
</head>

<body>
  <div id="root"></div>
  <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
  <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
  <script src="https://unpkg.com/babel-standalone@6/babel.js"></script>
</body>
<script type="text/babel">
const numbers = [1, 2, 3, 4, 5];
const listItems = numbers.map((number) =>
  <li key={number.toString()}>{number}</li>
);
  console.log(listItems)
  ReactDOM.render(
    <ul>{listItems}</ul>,
    document.getElementById('root')
  );
</script>

</html>